This 1965 photograph shows Qasr Al-Hosn, the traditional fortress residence of the shaykhs of Abu Dhabi. Originally built as a watchtower in about 1761 by Shaykh Dhiyab bin Isa, it was expanded into a small fort in about 1793 by his son, Shaykh Shakhbut bin Dhiyab, and at that time was made the permanent residence of the ruler of Abu Dhabi. It was further expanded in the late 1930s following the influx of revenue from oil concessions, and it remained the main palace of Abu Dhabi until 1966. Seen flying in the desert breeze is the flag of Abu Dhabi, which combines the traditional red of the Muslim emirates with white, which Great Britain, under the General Maritime Treaty of 1820, asked the Trucial States, as the emirates became known, to add to their flags as a sign of their peaceful intentions. The photograph is from the Colonel Edward "Tug" Bearby Wilson Collection in the National Library, Abu Dhabi Authority for Culture and Heritage, and was taken by Wilson. Colonel Tug Wilson (1921–2009) was a British army officer who, in the 1960s, was seconded to the government of Abu Dhabi to help build the national defense force. He was a personal friend of the ruler of Abu Dhabi, Shaykh Zayed bin Sultan Al Nahyan (1918–2004), with whom he shared interests in falconry and horseback riding.